Dr. Dávid Keller1, Emese A. Fazekas2, Prof. Árpád Dobolyi1,2
1 Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest
2 MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Eötvös Loránd University and the Hungarian Academy of Sciences, Budapest
Introduction: In a previous study, we determined the posterior intralaminar complex of the thalamus (PIL) and its neurons containing tuberoinfundibular peptide of 39 residues (TIP39) as a relay station of socially relevant sensory information innervating and activating oxytocin-secreting neurons upon social encounter.
Aims: Our present aim was to identify and functionally characterize neuronal projections from the PIL during stress-free social interaction in rats.
Method: We examined the interactions between familiar female rats. The brain activation patterns were determined following direct interaction, and also with the exclusion of physical interaction using the c-Fos technique. We also determined the effect of chemogenetic stimulation of the PIL using the DREADD technique on the social behavior and the brain activation pattern. In addition, anterograde tract-tracing from the PIL was performed where TIP39-immunoreactivity in labeled fibers was examined with double immunohistochemistry.
Results: We found that neurons in the PIL project to different elements of the social brain network, such as the somatosensory and the infralimbic cortices, the lateral septal nucleus, the medial amygdala, the preoptic area, the paraventricular and dorsomedial hypothalamic nuclei. Significantly higher level of activation upon social encounter was found in the medial amygdala, the somatosensory and infralimbic cortices, compared with control animals without any social interactions. The chemogenetic stimulation of the PIL resulted in the activation of two socially relevant brain regions, the infralimbic and somatosensory cortices. Stimulation of the PIL also influenced the behaviour of the animals as it increased the duration of social interactions.
Conclusion: The results suggest that the PIL may convey socially relevant information to several other brain regions. The PIL and other brain regions activated by social encounter may participate in the control of social behaviors, contributing to the regulation of its complex neuronal mechanism.
Support: Excellence Program of the Semmelweis University, NKFIH-4300-1/2017-NKP_17 and OTKA K116538.
Doctoral School: János Szentágothai Doctoral School of Neurosciences
Program: Neuromorphology and Cell Biology
Supervisor: Árpád Dobolyi
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